Is there any app that can do bookkeeping and inventory something like quickbooks? I tried easy book but it kinda sucks....

Can't help you specifically but I would caution you about using the iPad for any serious accounting tasks. Applications like Quickbooks are far too complex to be handled in iOS. If all you're trying to do is simple double entry bookkeeping and it's not a mission critical requirement, you may be able to find something that works. But anything more complicated is likely to need backup in a real computer. You might want to consider something like LogMeIn or Splashtop that would enable you to view and manipulate an accounting application on your computer.